This invention relates to a communication system such as a teletex system in which transmission and reception of documents are effected between word processors through public communication lines and more particularly to method and apparatus for re-transmission operations to be performed in the event of a wrong telephoning.
In a communication system having an automatic transmission/reception function to perform data communications through telephone lines, a re-transmission operation is performed a predetermined period of time after an addressee called for communications is determined busy (calling) or when communications is interrupted after an addressee has responded. Depending on situations, the re-transmission operation is repeated several times. The communication interruption requiring a re-transmission is due to abnormality of an addressee station, connection transfer to the telephone set side preset by means of a communication unit/telephone set switching device in the addressee station, or a wrong telephoning caused when an operator on an addresser side inadvertently sets a wrong addressee telephone number. Of the above causes, the wrong telephoning is seriously troublesome.
Essentially, the communication system having the automatic transmission/reception function is unattended to run throughout 24 hours. Unless urgent, the time for transmission of documents is designated to advantage of economy such that the documents are transmitted within a midnight discount time zone. Accordingly, even when a wrong telephone number has been set by the operator, the communication unit calls an addressee of the wrong telephone number when the designated time is up. Naturally, the wrong telephoning forces a person or an attendant to respond and gives the attendant serious trouble. In addition, responding by the attendant leads to communication abnormality and the addressor tries to call again at the termination of a predetermined period of time in order to re-transmit a document to the same addressee.
Thus, the frequently repeated midnight wrong telephoning gives the addressee socially problematic, serious trouble.
Conventionally, as disclosed in JP-A-No. 60-223375, an approach to the above problems has been proposed wherein when a predetermined transmission procedure is not completed within a predetermined period of time following circuit connection, a wrong telephoning is assumed and a flag to this effect is set even if an addressee attendant responds and thereafter when a transmission (re-transmission) to the same addressee is again performed and similarly decided to be a wrong telephoning, the third and ensuing transmissions (re-transmissions) are inhibited. With this proposal, however, the wrong telephoning assumed in the first communication operation always connects to the second calling to the same addressee even when time runs, at the time of execution of the first communication operation, within the midnight discount time zone and so the wrong telephoning is conclusive, thereby unreasonably maximizing trouble given to the addressee.